How big is the pool and how extensive is the pollution usually ? Please click on the applicable button. Further below there is a help on how to choose the size of the pool. Large-scale pollution: Large pool Medium pool Small pool Soiling in places: Large pool Medium pool Small pool Large pool Round pool with more than 5 m diameter Swimming pool with more than 5×4 m More than 20m² area Medium size pool Round pool up to 5 m diameterSwimming pool up to approx. 5×4 mUp to circa 20m² area Small pool Round pool up to 3 m diameterSwimming pool up to approx. 2×4 mUp to approx. 8m² area